Stimuli-sensitive polymer hydrogels exhibit a notable volume phase transition in response to minor changes in environmental parameters of aqueous solutions, making them ideal for smart sensing layers. These hydrogels can be integrated with various micromachined transducers to create cost-effective, miniaturized, and versatile chemical microsensors suitable for diverse target analytes. However, for real-world applications, there is a need for long-term stability and rapid response in these sensors, which many existing hydrogel-based sensors fail to achieve. Volume 50 of the Dresdner Beiträge zur Sensorik series focuses on piezoresistive hydrogel-based sensors and proposes two approaches to address current limitations. The first approach involves modifying the hydrogel material properties through the fabrication and integration of macroporous and clay-nanocomposite hydrogels. The second approach employs a system-based method using force compensation, where the responsive hydrogel structure operates within a controlled feedback system. Both approaches are thoroughly examined in terms of theory, technology, and implementation, ensuring adaptability to hydrogel sensors with various transducer types.
